Clay gum, commonly known as rubber clay, is a phenomenon where excessive moisture in clay, after being crushed, forms an elastic-plastic soil layer due to the inability of the pore water to drain. Its texture resembles chewed gum, adhering to surfaces and being difficult to remove; it becomes sticky and mushy when wet, and has a soft, sticky, and elastic nature. This type of soil is a challenge in non-excavation construction, often found at the bottom of riverbeds. Since these areas are commonly used for non-excavation construction, attention is required.

Two critical parameters of directional drilling machines are torque and thrust. During the construction process, operators rely on feedback from these two parameters to assess the progress of the project and make process improvements. However, when encountering clayey soil layers, the torque and thrust of the drilling machine do not show significant changes in a short period, posing a challenge for operators to timely detect soil condition changes and take appropriate measures.

Boring beneath the soil layer of this stratum often encounters the problem of soil chips, which are not effectively flushed out or dispersed in the mud slurry. This leads to rough boreholes, which are detrimental to subsequent processes. Additionally, if the sticky clay adhering to the drilling tools and rods is not promptly addressed, the adhesion effect intensifies, potentially forming thick encapsulating layers that greatly consume torque, resulting in inability to bore holes or even halting operations. Especially, such strata are commonly found at the riverbeds, and repairs and rectifications in such cases can be costly. Therefore, it is crucial to have comprehensive geological information prior to construction and to take preventive and emergency measures for the sticky clay.

To combat clay, the primary approach is to formulate and utilize appropriate drilling mud. The mud is mixed in a specific ratio of expansive clay and water with mechanical and maintenance blades. Its function is to lubricate the drill bit, reduce wear on the formation, facilitate drilling, and expel debris along the way, forming a mud cake on the borehole wall to stabilize it for enlargement. For clay formations, the mud formulation must be adjusted based on the actual environment, with timely modifications to the mud recipe according to the drilling rig's feedback on torque and drilling force, and the addition of anti-caking agents. This ensures the mud can promptly remove clay from the drill tools and stabilize the pilot hole to ensure the continuation of subsequent operations.